Apple co-founder and former CEO Steve Jobs threatened Palm CEO Edward Colligan with patent litigation if he did not agree to stop poaching Apple employees, according to a court filing that was made public on Tuesday.

Confidential emails between the pair, along with documents from Adobe and Google, have surfaced in a civil lawsuit that claims a number of major companies in Silicon Valley violated antitrust rules by entering into agreements not to recruit each other’s employees. Five employees are now fighting for class action status and damages for lost wages as a result of the “no-hire” agreements.